The invention relates to a vacuum coating apparatus with a target formed on a basis of tin or lead by which one or more layers are applied to a substrate by sputtering in a reactive atmosphere.
It is already generally known in vacuum coating apparatus the principle of cathode sputtering to use a reaction gas in addition to a sputtering gas such as argon. O.sub.2, N.sub.2, CH.sub.4 or H.sub.2 S among others are used as the reactive gases for sputtering. In the case of tin targets, oxygen is used as the reactive gas in order to apply a tin oxide coating to the substrate. This reactive sputtering process is greatly appreciated in certain manufacturing processes, because it permits the preparation of compounds in an especially repeatable manner, i.e., it leads to transparent coatings. In the use of tin and/or lead targets in conjunction with oxygen as the reactive gas, an oxide coating also forms on the surface of the target after a brief processing time, so that after comparatively long use the target has to be cleaned. Consequently the manufacturing process becomes relatively expensive due to the short length of time for which the target can be used.